Our invention relates to a muting circuit, and particularly to a muting circuit for muting a radio receiver loudspeaker during transmission of data signals.
Many communication systems use data to indicate conditions or functions. For example, in a radio communication system having a fixed base station and one or more mobile stations, the base station may wish to make a transmission directly to only one mobile station. This can be achieved by transmitting a data signal identifying the one mobile station at the beginning of the transmission, and by then sending a voice message. Or only a data signal identifying a station and providing a function or making an inquiry may be transmitted. In any case, it is desirable that the identified mobile station, as well as others, not reproduce the data sounds in the receiver loudspeaker, as such sounds are unnecessary and may be annoying.
Accordingly, a general object of our invention is to provide a new and improved muting circuit for radio receivers.
Another object of our invention is to provide a new and improved muting circuit for radio receivers which are used in a system where data may be or is transmitted.
In a radio system such as described above, transmissions may also be made without data, in which case an operator will begin to speak almost as soon as the transmission begins. In such cases, the receiver should be unmuted very quickly so as to reproduce the voice transmissions.
Accordingly, another object of our invention is to provide a new and improved radio receiver muting circuit that provides a fixed muting time at the beginning of a received transmission, and that continues to mute the receiver if data is received, or that unmutes the receiver if no data is received but the transmission is continued.